Method for recovery of tungsten from spent catalysts
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United States of America Patent
Stats
-
Aug 3, 1999
Issued Date -
N/A
app pub date -
May 26, 1992
filing date -
Sep 24, 1990
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A method for recovering tungsten from a tungsten containing spent catalyst comprises digesting the catalyst in aqueous sodium hydroxide solution wherein the mole ratio of the sodium hydroxide to the tungsten contained in the spent catalyst is from about 2.6 to about 4.2 and wherein the amount of water is sufficient to dissolve the subsequently produced sodium tungstate, at a temperature of at least about 90.degree. C. for a length of time of at least about 1 hour to convert greater than about 77% by weight of the tungsten contained in the spent catalyst to sodium tungstate and form a sodium tungstate solution thereof and a residue containing the balance of the starting tungsten, and separating the sodium tungstate solution from the residue. Essentially all of the tungsten is recovered as sodium tungstate by first grinding the catalyst prior to the digestion and by using a mole ratio of sodium hydroxide to tungsten of about 3.8 to 4.2.
First Claim
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